Porous oxygen lance



July 24, 1962 E. B. HUDSON POROUS OXYGEN LANCE 5 Sheets-Sheet 1 FiledMarch 2. 1959 INVENTOR. fan MAB, f/uasa/v,

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July 24, 1962 u so 3,045,997

POROUS OXYGEN LANCE Filed March 2. 1959 3 Sheets-Sheet 2 INVENTOR.Z'am/v .5. Hausa/v,

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United States Patent 3,@45,997. Patented July 24, 1962 ice Ohio

Filed Mar. 2, 1959, Ser. No. 796,343 7 Claims. (Cl. 266-34) Thisinvention relates to apparatus for discharging a gas into an open hearthfurnace or a converter type vessel, and relates more particularly to theprovision of a lance by means of which oxygen may be injected onto thetop of a molten iron charge in an oxygen process converter.

In the oxygen converter method of steel making, which is sometimesreferred to as the L-D (Linzer Dusen Verfahren or Linz-Donawitz)process, pig iron is converted into steel by directing a stream ofoxygen downwardly into a bath of metal from above. The apparatusgenerally used for this purpose is a structure or lance having adischarge nozzle positioned near the surface of the molten metal. Suchlances are constructed from a metal having high heat conductivity, suchas copper, and are provided with water cooling passageways to preventthe metal from melting or burning away during use. However, since thetemperatures of the molten metal during the oxygen operation areexceptionally high, ranging up to 6000-8000" F., the Water cooled lancescurrently in use fail in a very short time.

The principal cause of lance failure lies in the fact that theconductivity of the metal from which the lance is made is far below thatrequired to remove excess heat from the external surfaces of the lanceto the cooling water. This is indicated by the relatively lowtemperature rise of the cooling water in view of the high temperature onthe heat exposed outer surfaces of the lance. Copper, which has a veryhigh rate of heat conductivity, melts at 1982" F. and there areindications of melting or burning of the outer surfaces of a copperlance after a relatively short period of use. Readily available metalsother than copper provide an even more acute problem in that theirconductivity or K values are less than that of copper. While there aresome metals available which have a higher K value, their cost isprohibitive.

In accordance with the instant invention, I eliminate the foregoingdifficulties by conducting the coolant directly to the exposed surfacesof the lance. This is accomplished by providing a lance having a porouswall structure through which the coolant may be passed, the coolant thusbeing brought into direct con-tact with the outermost or hot surfaces ofthe lance, thereby maintaining the temperature'of the lance structure atapproximately the same temperature as the coolant. With the porous wallstructure, it is no longer necessary to transmit heat through the wallstructure to the coolant and the K value is no longer a problem. For acoolant I prefer to employ steam which may be readily supplied underpressure and forced through the porous wall structure of the lance. Thetemperature of the steam, even if super heated under high pressure, willnevertheless be well below the melting point of porous metal and willcool it sufficiently to prevent melting or burning.

In addition to protecting the lance structure from excessive heat, theinstant invention also solves other problems encountered in basic oxygenprocessing. When blowing molten metal with oxygen, the nozzle of thelance will normally become heavily encrusted with splashes of moltenslag and metal which serve to diminish the heat transfer efliciency ofthe lance, thereby further decreasing its useful life. In accordancewith the instant invention, the escaping steam or other cooling fluid asit passes through the walls of the lance under pressure will prevent thesplashes of slag in metal from sticking to the lance. However, if byaccident a burn does occur on the lance surface, thereby reducing itswall thickness, then at this point the decreased wall thickness willincrease the steam velocity at the point of damage, thereby arrestingfurther lance deterioration.

in this connection, it may be observed that another advantage in theinvention lies in the fact that a wide range of lance protection to meetmost of any temperature conditions encountered can be provided byvarying the velocity of the coolant as it leaves the outside surface ofthe nozzle structure. For example, where the coolant fluid is steamhaving a pressure of 40 p.s.i.a. and a temperature of 276 F., the steamvelocity will be approximately 10 fps. as it leaves the outside surfaceof a /2" porous wall. By varying the velocity of the cooling fluid,whether it be steam, an inert gas, or compressed air, in accordance withthe temperatures encountered, a wide range of lance protection can beprovided.

The instant invention also solves another problem encountered in basicoxygen processing, namely, the fumes which are given off by the moltenmetal during the blowing operation. These fumes are contaminated withvarious impurities which must be cleaned before being released to theatmosphere. The use of a gaseous coolant and its release in the furnaceor converter results in the formation of a blanket or layer whichcompletely surrounds the oxygen jet between the nozzle and the surfaceof the molten metal, thereby providing an additional control of thefumes which is not possible in the conventional lance construction.Where the coolant is steam a further advantage is realized in that thesteam increases the particle sizes of the impurities in the fumes andmakes the use of bag filters possible for filtering purposes.

In the past, there has been some reluctance to use oxygen lances in theconventional open hearth furnace, since considerable roof damage occurs,reducing the availability of the furnace. With the use of a fluid-cooledlance, the escaping fluid provides a heat barrier, thereby providingadded protection to the open hearth roof.

In accordance with the foregoing, it is a principal object of myinvention to provide for enhanced lance protection by conducting acoolant fluid into direct contact with the outermost or hot surfaces ofthe lance.

A further object of the invention is the provision of a lance structurewherein the coolant is transmitted directly through the walls of thelance, the lance structures themselves embodying various novel featuresof construction and arrangement of parts inclusive of a whollysteamcooled lance and a lance incorporating a steam-cooled nose andwater-cooled walls.

The foregoing together with other objects of the invention which willappear hereinafter or which will be apparent to the skilled worker inthe art upon reading these specifications I accomplish by thoseconstructions and arrangements of parts, and by those procedures ofwhich I shall now describe certain exemplary embodiments.

Reference is now made to the accompanying drawings wherein:

FIGURE 1 is a side elevational view of a lance constructed in accordancewith the invention.

FIGURE 2 is a side elevational view with parts broken away of a waterand steam-cooled lance.

FIGURE 3 is a vertical sectional view through the porous nose of thelance, illustrating the use of a plurality of grades of porous metal.

FIGURE 4 is a side elevational view with. pants broken 'away of amodified form of lance structure.

FIGURE 5 is -a sectional view taken along the line 5-5 of FIGURE 4.

FIGURE 6 is a partial elevational view of another modification of thelance.

FIGURE 7 is an end view of the lance shown in FIG- URE 6.

FIGURE 8 is an enlarged partial sectional view taken along the line 88of FIGURE 7.

FIGURE 9 is a sectional view taken along the line 99 of FIGURE 8.

FIGURE is an enlarged sectional view of a mounting ring forming a partof the nozzle structure illustrated in FIGURE 8.

FIGURE l l is an enlarged sectional view of the inner nose memberforming a part of the nozzle structure.

In accordance with my invention the solid walls and/ or the nose of aconventional lance are replaced by a porous structure wherein thecoolant fluid passes through interstices in the porous material. Apreferred material is porous bronze which is commercially available andis produced by bonding together, metal-to-metal, small bronze sphereswhich are carefully graded to the same size and then sintered by powdermetallurgy methods. The grades are determined by the size of thespheres, which in turn control the size and number of flow passages orinterstices per square inch of metal. For example, porous bronzemanufactured by the Moraine Products Division of General MotorsCorporation under the trademark Moraine Porous Metal is currentlyavailable in four grades, ranging from coarse to very fine. The porousmetal is graded on a particle stopping basis and ranges from .0O2.005"(coarse) to .000 1.0005" (very fine). As will be explained more fullyhereinafter, various parts of the lance structures may be formed hromdifferent grades of the porous metal so as to proportion the coolantflow to suit the temperatures encountered. For example, the tip or noseof the lance which is nearest the molten metal can be made from a moreporous grade of metal, whereas the more remote parts of the nozzle canbe made from less porous grades, thereby restricting the coolant lflowin areas where lesser temperatures are encountered.

Referring now to FIGURE 1 of the drawings, I have therein illustrated alance having a body or head 1, an elongated tubular nozzle 2 terminatingat its free end in a tip or nose 3, the entire structure being adaptedto be suspended within a furnace or converter by means of a removableeye ring 4 threaded into the upper end of the lance body.

In the embodiment illustrated in FIGURES l and 2 the body or head 1 ofthe lance is composed of a plurality of body sections, the uppermostsection 5 having an oxygen chamber 6 to which oxygen is supplied throughan inlet passageway 7 from a source not shown. A centrally disposedconduit -8 extends downwardly from the oxygen chamber and serves todeliver the oxygen to the nose 3 of the lance where it is dischargeddirectly onto the surface of the molten metal 9 as a stream 10.

A second body section 11 is secured immediately beneath body section 5,the section 11 being provided with a hub portion 12 which surrounds theupper end of cond-uit 8, the conduit being conveniently secured in placeby means of a nut 13. The conduit 8 is preferably provided with anannular shoulder 14 which engages an O ring 15 positioned to makesealing contact with the outer surface of the conduit. The body section11 defines a steam chamber 16 to which steam is delivered through inletpassageway 17. A second conduit 18 extends downwardly from chambers 16to the nose of the lance, the conduit 18 surrounding conduit 8 anddefining an annular passageway 19 therebetween through which steam fromthe chamber 16 may flow to the nose of the lance. At its lower end theconduit 18 is preferably flared outwardly, as at 20, and is secured tothe lower end of nozzle 2.

A third body section 21 is secured immediately beneath body section 11and provided with a hub 22 surrounding the upper end of conduit 18, thehub mounting a stufiing box 23 which provides a tight seal between thehub and the conduit. The third body section provides a water inletchamber 24 to which water is supplied through inlet orifice 25. A thirdconduit 26 extends downwardly from chamber 24, the conduit 26surrounding the second conduit 18 and defining an annular passageway 27therebetween. The conduit 26 also lies in spaced relationship withrespect to the Wall surfaces of tubular nozzle 2 to define an annularpassageway 28 therebetween. At its lower end the conduit 26 terminatesshort of the flared lower end of conduit 18, thereby providing aconnection between passageways 27 and 28 so that water flowingdownwardly through passageway 27 will reverse its direction and flowupwardly through passageway 28 wherein it will be in heat exchangerelationship with the walls of nozzle 2. At its upper end, thepassageway 28 opens into a discharge chamber 29 formed in a fourth bodysection 30, the chamber having an outlet orifice 3'1. A stuffing box 32provides a tight seal between the conduit 26 and the walls of bodysection 30.

In this embodiment of the invention, the tubular nozzle 2 is preferablyformed from centrifugally cast copper to insure high heat conductivityand, as already indicated, the walls of the nozzle are cooled by meansof water flowing through inlet chamber 24, down passageway 27 and thenupwardly along passageway 28. The nose of the lance is, however, cooledby steam flowing downwardly through passageway 19, the nose 2 beingconstructed of porous bronze material of the character alreadydescribed. As best seen in FIGURE 3, the nose 3 has a central bore 33which receives the lowermost end of oxygen conduit 8, the oxygen flowingthrough the conduit being expelled through orifice 33a in the nose. Theorifice 33a is machined, and the machining acts to seal the intersticesat the machined surface, thereby preventing the exchange of oxygen orsteam through oxygen bore 33a. The nose is also provided with an annularcavity 34 which is in communication with the passageway 19, so thatsteam flowing downwardly through the passageway will enter the cavity 34and pass through the porous walls 35 of the nose. If desired, the entirenose structure may be formed from the same grade of porous bronze, or,where the temperatures encountered permit it, the lowermost portion ofthe nozzle, which is indicated at 36, may be formed from a firstrelatively coarse grade of porous metal whereas the remainder of thenozzle, indicated by the reference numeral 37, may be formed from asecond and less coarse grade of metal, thereby permitting a greater flowof the coolant through the portion of the nose nearest the molten metal.As will be evident from FIGURE 2, spacers 38 may be provided to supportthe lowermost free end of conduit 26.

In FIGURES 4 and 5 of the drawings there is illustrated an embodiment ofthe invention wherein the entire nozzle structure is formed from porousmetal. In this embodiment, the eye ring 4 suspends a unitary hollow body40 having an oxygen chamber 41 in communication with an inlet passageway42, there being a centrally disposed oxygen conduit 43 extendingdownwardly to the nose of the lance, the conduit being secured to thebody by means of a fitting 44. The body 40 is also provided with a steamchamber 45 in communication with an annular passageway 46 definedbetween the outer surface of conduit 43 and a second conduit 47 thelower end of which terminates short of the nose 2 so as to providecommunication to a return passageway 48 formed between the walls ofconduit 47 and the inner surfaces of nozzle 50. In this instance theentire nozzle 50 is formed from porous metal. If desired, the same gradeof metal may be used throughout the length of the nozzle or, asillustrated, it may be composed of a plurality of sections 50a, 50b and500 composed of diflerent grades of porous metal progressing upwardlyfrom a relatively coarse section adjacent the nose to a relatively fineuppermost section adjacent the body, thereby controlling the rate ofcoolant flow in accordance with the proximity of the lance to the moltenmetal. As seen in FIGURE 5, spacers 51 may be provided to support theconcentric conduits 43 and 47.

Referring again to FIGURE 4, the protective boundary layer of steam isshown at 52, the layer completely surrounding the external surfaces ofboth the nose 3 and the walls of nozzle 5%, thereby both cooling thesesurfaces and protecting them from splashes of molten metal. The blanketof steam also completely surrounds the oxygen jet which impinges uponthe molten metal, the surrounding layer of steam forming a blanket overthe fumes which are generated by the molten metal. Slag is indicated at53.

FIGURES 6 and 7 illustrate still another modification of the inventionwherein the nose 55 is provided with a plurality of oxygen outlets 56arranged to diffuse the oxygen stream and thereby minimize splashing. Inthis embodiment, the nozzle is composed of a plurality of juxtaposedrings 57 which may be formed from either porous material or fromconventional refractory materials.

As best seen in FIGURE 8, the centrally disposed oxygen conduit 58 isprovided at its lower end with an inner nose member 59 (see also FIGURE11) having a plurality of openings 60 therein corresponding in positionand number to the openings 56in the nose 55. The inner nose member 59may be conveniently threaded on the lower end of conduit 58. As seen inFIGURE 10, inner nose 5 9 also supports a mounting ring 61 having aninner sleeve 62 adapted to surround the upper portion of the inner nosewith lower edge seated on the shoulder 63 of the inner nose. Themounting ring also has an outer sleeve 64 which is spaced from the innersleeve by means of webs 65; and, as seen in FIGURE 8, the outer sleevelies in prolongation of the steam conduit 66. It will be noted that thelower end of the outer sleeve 64 turns inwardly, as at 67, so that steamflowing downwardy through conduit 66 will flow into the chamber 68between the nose 55 and the inner nose member 59, whereupon it will passoutwardly around the inturned end of sleeve 67 and flow upwardly throughannular passageway 69. Tubes 70 extend between the openings 56 in theouter nose and the openings 60 in the inner nose member through whichthe oxygen flows.

The mounting ring 61 also includes a series of Webs 71 which support anannular shoulder 72 against which the lowermost refractory ring 57 isseated. The several refractory rings are notched, as at 73, so that theywill fit together. If the refractory material is of imperforatecharacter, the notches or joints 73 provide spaces through which steammay escape, as indicated by the arrows 74, thereby again enclosing thenozzle by steam. It will be understood, of course, that the outer nose55 will be formed from porous material through which the coolant steamwill pass. If desired, one or more of the rings 57 may also be formedfrom porous material.

As should now be readily apparent to the skilled worker in the art, theproblem of heat conductance in an oxygen lance is substantiallyeliminated by conducting the fluid coolant directly to the outermost orhot surfaces thereof. By using a wide range of fluid pressure, theinvention provides protection to the lance even though the temperaturesof the molten metal range up to 600045000 F. At the same time fumes fromthe blowing operation are blanketed with the coolant and hence may bemore readily controlled and removed.

Modifications may, of course, be made in the invention without departingfrom the spirit and purpose of it. Thus, while steam has been disclosedas the preferred coolant, other cooling fluids may be readily employedwithout departing from the spirit of the invention. Similarly, whileporous bronze has been disclosed as a preferred material from which toform the nose and wall surfaces of the nozzle, other porous metals andporous refractories may be employed. It will also be obvious thatmodifications may be made in the construction of the lances, and theporosity of the nose and wall parts thereof may be varied as required.

Having, however, described my invention in certain exemplary embodimentswhat I desire to secure and protect by Letters Patent is:

1. A lance for use under conditions of high temperature, said lancehaving an elongated tubular nozzle structure terminating in a nose, saidnozzle structure comprising a plurality of porous sections formed fromporous material having minute interstices therein through which a fluidcoolant such as steam may be transmitted, said porous sections being ofvarying degrees of porosity, and means within said nozzle structure fordelivering a fluid coolant to the inner surfaces of said poroussections, whereby said coolant may pass through the interstices thereinso as to envelope the exterior surfaces of said nozzle structure in aprotective blanket of the coolant fluid.

2. The structure claimed in claim 1 wherein the said porous sectionsprogress from a relatively coarse section adjacent the nose of saidnozzle to a relatively fine section at the end of said nozzle remotefrom said nose, whereby to control the rate of coolant flow inaccordance with the proximity of the lance to a source of heat such asmolten metal in an open hearth furnace in which said lance is suspended.

3. An oxygen lance for use under conditions of high temperature, saidlance having an elongated tubular nozzle structure terminating at oneend in a nose, at body member secured to the opposite end of said nozzlestructure, an oxygen chamber in said body, an oxygen discharge orificein said nose, a first conduit centrally disposed in said tubular nozzlestructure and having one end thereof in communication with said oxygenchamber and the opposite end thereof in communication with said orifice,a coolant chamber in said body, a second conduit surrounding said firstconduit in spaced relation thereto and having one end in communicationwith said coolant chamber and its opposite end positioned so that acoolant fluid passing therethrough will impinge upon the inner surfacesof said nose in an area surrounding the orifice therein, said last namedarea of said nose being formed from a porous metal having intersticestherein through which the coolant fluid may be transmitted from theinner to the outer surfaces of said nose, said second named conduitbeing surrounded by and lying in spaced relation to the wall surfaces ofsaid tubular nozzle, the wall surfaces of said nozzle being composed ofa plurality of tubular sections formed from porous material havinginterstices therein through which the coolant fluid may be transmitted,said tubular sections having varying degrees of porosity, the spacebetween said second conduit and said tubular nozzle being incommunication with the end of said second conduit at a point adjacentsaid nose, whereby coolant flowing through said second conduit to saidnose will then flow through said space in reverse direction for contactwith the inner surfaces of the tubular nozzle.

4. An oxygen lance for use in the oxygen converter method of steelmaking, said lance having an elongated nozzle structure including agenerally conical nose, a plurality of oxygen discharge orifices in saidconical nose, the conical wall surfaces at least of said nose beingformed from porous metal having interstices therein through which acoolant fluid may be transmitted from the inner to the outer surfacesthereof, a first conduit extending through said nozzle structure, saidfirst conduit terminating at its lower end in an inner nose member lyingin spaced relation to said conical nose to form a cavity therebetween,said inner nose member having a plurality of openings thereincorresponding in number to the orifices in said conical nose, tubes insaid cavity connecting the orifices in said conical nose and the openingin said inner nose member, a second conduit within said tubular nozzlesurrounding said first conduit, said second conduit lying in spacedrelation both to said first conduit and to the wall surfaces of saidtubular nozzle to provide annular passageways therebetween, saidpassageways at their lower end being in communication with the cavitybetween said conical nose and said inner nose member, whereby a fluidcoolant will flow through said annular passageways and said cavity, saidnozzle structure being composed of a plurality of concentric ringsformed from a refractory material and loosely fitted together one uponthe other so as to permit the escape of the fluid coolant therebetweenat spaced apart intervals along the length of said nozzle structure, anda mounting ring surrounding said inner nose for supporting saidconcentric rings.

5. An oxygen lance for use in the oxygen converter process of steelmaking, said lance having a plurality of fluid delivery chambers at oneend and an elongated nozzle depending therefrom, a centrally disposedoxygen delivery tube extending downwardly through said nozzle from oneof said chambers but terminating short of the bottom of said nozzle, aporous nose piece having at least an outer wvall and a bottom wallextending downwardly below said oxygen delivery tube and outwardlybeyond the periphery thereof, said porous nose piece having at least oneorifice therein connected to said oxygen tube for the delivery of a jetof oxygen downwardly :from the end of said lance, a first concentrictube srrounding said oxygen delivery tube and connected to a second ofsaid fluid delivery chambers and coacting with said oxygen delivery tubeto form a passageway for steam, said first concentric tube terminatingdownwardly in an open end within said porous nose piece so as to deliversteam to the interior of said nose piece, the exterior surface of saidelongated nozzle being defined by an outer casing concentric with andspaced from said first concentric tube to define a passagewaytherebetween connected to one of said chambers, and supplementarycooling means in conjunction with said outer casing for cooling itthroughout its length.

6. The lance structure claimed in claim 5 wherein said supplementarycooling means comprises an outer casing of perforate character, andwherein the passageway between said outer casing and said firstconcentric ring is connected to the chamber supplying steam to said nosepiece.

7. The lance structure claimed in claim 5 wherein said supplementarycooling means comprises water cooling means connected to a third of saidfluid delivery chambers.

References Cited in the file of this patent UNITED STATES PATENTS2,548,231 Avery et al. Feb. 6, 1951 2,807,506 Gehring Sept. 24, 19572,828,956 Bieniosek et al. Apr. 1, 1958 2,829,960 Vogt Apr. 8, 19582,863,656 Cox Dec. 9, 1958 FOREIGN PATENTS 755,416 Great Britain Aug.22, 1956

